An amendment changes or completes an earlier filing. Its form type is the original's with /A added: 10-K/A, 10-Q/A, 8-K/A, SCHEDULE 13D/A.
Why companies amend
- To add what was left out. A common 10-K/A adds Part III (directors, pay, ownership) when the proxy statement will not be filed within 120 days of the year end.
- To correct. An amended 10-K or 10-Q can carry restated financial statements. See restatement.
- To follow up. An 8-K/A often adds the financial statements of a business the company bought, which it may file later than the original 8-K.
- To update. A Schedule 13D/A reports a material change in a large holder's position or plans.
Reading it
Check the explanatory note at the start: it says why the amendment exists and what it changes. An amendment that only adds Part III says nothing new about the numbers. One that restates them does. Listed keeps the figures from every filing, and each figure's note names the filing it came from.